Dynamax. There is no substitute!
Damn near close to stock at idle and only slightly louder under throttle. It's not so much that it's "Louder" actually, more than anything, a Dynamax will lower the tone of the exhaust. It'll sound a lot deeper. More of a low pitch rumble. Even at wide open throttle, it's not very loud. But it has a very nice, how should I say it, "REFINED" sound.
Not loud and raspy like Flowmaster. Just a nice subdued tone. Reminds me of how the newer vettes sound like with the factory exhaust.....
The ultra-flow stainless steal mufflers by Dynomax are one of, if not THE best flowing mufflers on the market and it's just about the quitest muffler you can buy short of a stock replacment. They're a bit pricey though.
The Dynomax "super-turbo" mufflers are pretty cheap and I've seen them behind cars putting out 450+ hp so ibviously, they're not much of a restriction either....
Dynomax have always been the mufflers to go with when you wanted great performance and a nice "mellow" exhaust tone.